Theoretical Investigation of the Behavior of Reinforced Concrete Ledge Beams

This paper presents a theoretical investigation of the behavior of reinforced concrete ledge beams that used finite element theory to model the nonlinear behav¬ior of reinforced concrete in all loading stages. The three main parameters were the effective thickness of the outer part of the web near the concentrated load where vertical hangers can effectively be placed; the contribution of diagonal bars to the hanging capacity of ledge beams; and the effect of the load eccentricity on the hanging capacity of ledge beams. The punch¬ing shear behavior of ledge beams was also analyzed using a plasticity-based nonlinear finite element model. Several experimental results were collected from the literature to support the finite element results. The paper also compares estimates of the hanging capacity of ledge beams and the punching shear capacity of ledges derived from the Egyptian Code of Practice for Planning, Design, and Construction of Bridges and Elevated Intersections, the American Association of State Highway and Transportation Officials’ AASHTO LRFD Bridge Design Specifications, and the PCI Design Handbook: Precast and Prestressed Concrete. Last, the paper presents a proposal for the effective thickness of the outer part of the web near the concen¬trated load where vertical hangers can be effectively placed.